The study on the eect of Ruthenium(Ru) in LaFeAsO

Abstract

We study the eect of Ru substitution at Fe site on LaFe1xRuxAsO compounds for x = 0, 0.25, 0.50, 0.75 and 1. We produce density of state (DOS), Fermi surface (FS) and a band structure based on Density Functional Theory(DFT). The result on the band structures show that Ru substitution changes the hole bands and not the elec- tron bands. One of the possible reason is perhaps that Ru substitution does not induce additional electrons, which is in agreement with NMR and resistivity measurement report. We conclude that the change inthe whole bands is the reason for suppressing eect of Ru. The DOS is much aected for over doped region(x > 0:50) around the Fermi level. For Ru = 0.50, the Fermi surfaces is close to nesting, and we calculated the value of Tc applying McMillan equation. The result in-dicates that the alloy can be a superconductor only for strong pairing potential( > 0:7).